3-phenyl-2-piperidones



Patented Oct. 3, 1950' 37PHENYL-2-PIPERID0NES Lewis A. Walter, East Orange, and Richard Barry, Arlington, N. J., assignors to Maltbie Laboratories,.lnc., a corporation of New Jersey N Drawing. Application December I Serial N0. 789,756

9 Claims. (01. 260-293) This invention relates to a new and useful composition of matter, namely, a substituted Z-piperidone of the formula:

wherein R represents an alkyl or .an aryl radical and R represents hydrogen, an alkyl or an aralkyl radical.

In the formula given above the positions are numbered as follows for thepurposes of the nomenclature herein used: the nitrogen shown at the bottom of the ring to which a substituent represented by R is bonded is the 1-position; the carbon atom connected to oxygen by a double bond is at the 2-position; and the carbon atom bonded to phenyl and to a substituent represented by R is at the 3-position, etc. Thus R represents a substituent bonded to the carbon at the 3-position and R, a substituent bonded to nitrogen at the l position.

These compounds have been tested pharmacologically and found to possess valuable anticonvulsant properties. They are also useful intermediates in organic syntheses, particularly in the preparation'oi similarly substituted piperidines.

The piperidones which are the subject of this invention" may be prepared by the catalytic hydrogenation of the appropriately substituted 'y-cyanobutyric esters, which in turn, are readily 3,3-diphenyZ-2-piperid0n This compound'is one in which R represents phenyl (Cal-I5) and R represents hydrogen.

A solution of 1 6 "g of methyl diphenylacetate in 200 ml. of peroxide-free dioxane'was treated with one gram of sodium methoxide and kept at 40-50 C. while 27 g. of acrylonitrile was added dropwise with stirring. When the addition was complete the mixture was heated at 60-70 C. for one hour. The dioxane was removed in vacuo and the residue was taken up in ether, washed with water, and dried. The ether was distilled to leave aresidue of methyl a,a-diphenyl-'y-cyanobutyrate which W crystallized frorn methanol, to.givematerialm ltine. at fi.- ..1

r v 2 Thirty grams of this ester, 160 ml. of methanol containing 30 g. of anhydrous ammonia, and .3 g. of Raney-nickel catalyst (finely divided nickel prepared for use as ahydrogenation catalyst) were sealed in a bomb and hydrogenated at 100- 125 C. under an initial hydrogen pressure of 1000 solve the product.

lbs/sq. in. until no more hydrogen was absorbed. The bomb was cooled, the pressure was released,

and the'contents of the bomb were removed and,

heated with enough additional methanol to disuncorrected, separated.

3 phenyZ-3-allcyl-2-p iperidones This group of compounds are those in which- R is an alkyl radical, specifically one having from 1 to 4 carbon atoms, which are presently considered the more desirable pharmacologically as compared with longer chain substituents, and

grams of 'acrylonitrile was added dropwise The mixture was heated at -70" C. for one hour- The material.

after theaddition was complete. was taken up in ether, washed with'water, dried and distille d to give methyl a-phenyl-aethy1-- cyanobutyrate, B. P. Mfr-150 C. .at 2 mm.

Forty grams of this ester, ml. of methanol containing 25" grams of anhydrous ammonia, and

3 grams of 'Rane'y-nickelcatalyst/was sealed. in. a bomband;hydrogenatedatlOO C. with hydro. gen at l000 lbs. pressure until no more hydrogen was absorbed. The bombwas coo1ed,thepres sure-releasedand thecontents of the bomb were removed. In this instance the product had-cryse. Y tallized out and, in order to remove the catalyst,

the mixture was heatedto boiling and filtered. On cooling, pure 3phenyl-B-ethyl-Z-piperidone separated as white crystals M. P. l2l-125'C. Ad-

ditional material was obtained by distilling the,

mother liquors. The product distilled at 140-150? C. at 2 mm.

a-p'henyl-a-n-propyl-v-cyanobutyrate QB. 140-1 1 915" C. at 0.5-1.0 mm. This esteron hydrogena- The catalyst was then removed by filtration, and on cooling crystals of 3,3-diphenyl-2-piperidone, M. P. 186- 87.5 'C.

cyanobutyrate, B. P. 160-165" C. at 1.5 mm. This ester on hydrogenation as described gave 3 phenyl-3-n-butyl-2-piperidone, B. P. 17 Q 17 5 C; at 2 mm., which melted at -72 C. when crystallized from hexone. Y

(d) In this particular compound, P's-represents an isobutyl radical (ClHQ). In preparing'this compound, methyl a-phenylisocaproate and-acryw lonitrile gave methyl a-phenyl-a-isobutyl-k =cy anobutyrate, B. P. -150" C. at 1 mm. This. ester on hydrogenation gave 3-phenyl-3-isobutyl- Z-piperidone, ;B. P, -160 C. at 2 m1 n., which melted: at 87438.5" 0. when crystallized -from arps:

1-alkyl-3-phenyl-3-ethyZ-2-piperidones- This group of compounds are-those inwhich R represents an ethyl radical (C2H5) and R repr-ese'n't's fanjalkyl -radical,- specifically one havin from f 1 to 4' carbonatoms, which are presently considered the more desirable-pharmocolo ically as compared with longer chain -subs tituents.--

(a) In this particular compound Ri-representsa, methyl radical (CI-1 In preparing this compound, two and three-tenths grams of sodium was finely powdered in' 500 ml. of toluene in the usual .manner... Twenty, grams of =3-phenyl-3- ethyhZ-piperidone, wasuadded and the mixture waslstirrednuntil all; theusodium had reacted. Thirteensgramsoftmethyl, sulfate was added and themixturewas refluxed for,, an.hour. The toluene solution was washedwvith; dilute ammonia, dried,sand-distilledtogivelemethylei ephenyldethyl-2.-.piperidone, ,B. P'.-12 5 -.l3,()? 0, 3,112. mm, Thismaterial. wascrystallizedjrom ether ligroin and melted-at. 545-563; C.

(b). .In this particular compoundRf; represents an ethyl. radical .,(C2I-I5) This, compound may be prepared, Icy-treatment of s the, sodium derivative of.. 3-.pheny1-3-ethy1:2-piperidone,, prepared as described;above,v withethyl sulfate to give 1- ethyl=-3,-phenyl-.3,-ethyl.-,2-piperidone, B. -P. 140:1(l7; C. at 3-mm-.. which .melted at,\50,- -51 C. when; crystallized from ethers-ligroin.

(a). -Inithisl particular. compound R; represents;-

a..n-..buty1 radical .(C4H9) This compound may be. prepared in a like. mannelghy treatm t. .01.

thed-ssodium derivative, of r3-,phenyl- 3,-ethyl 2-; 1 piperidone with:n-b1J.ty1;,.bromide to; give .zl-n'j butyl-3-phenyl-3@ethyle2epiperidone B..-. P; 154:.

?:6. at.2 mm..

EXAMPLEIV In this group of U compounds; R representsethyl as an exampleof alkyl substituentradicals,

andR- represents an aralkyl radical, specifically benzyl (CH2'C6H5). As an example of thepreparation of a compound of this-class l-benzyl- 3 phenyl-3-ethyL2-piperidone was also prepared by treatingthe sodium derivative of 3-phenyl-3-i ethyl-2-piperidone with benzyl chloride. It'dis tilled at C at 2 mm and meltedat- 50 -53 C.-when crystallized from ether-ligroim- 4 What is claimed is: a 1. A Z-piperidone having the formulai H2 A H2O C wherein-R represents a substituent at the 3-position which is selected from the group consisting ofaphenyl.and-alkyLradicals, and R represents a'substituent at-the-l-position which is selected from'thegroup consisting of hydrogen and alkyl and phe nallgylradicals, such compounds having valuable anticonvulsant properties.

2. A 2.piperidone having the formula wherein R is selected'from theygroup consisting of phenyl and alkyl radicals,;such compounds having valuable anticonvulsant properties.

3. A Z-piperidone having the formula wherein R representsan .alkyl group, such' comthis compound having 'valuabl'e anticonvulsant' wherein R is-selectedsfrom thegroup consisting ra ph n i and. ia k i adica s, :andMner im r pr sent ls pum u hco pounds-hay ns uab e n conru sant-- mp tien;.

-1A2 peridone-hav s t e f r u a.7

HzCrif C GEL.

wherein 'R is selected- =from--the group consisting ofr a phenyland-alkyl radicals, such compounds 1 having-valuable 'anticonvulsant propertiesw 7. 1-methy1-3-phenyl-3-ethy1-2-piperidone.

8. 3-pheny1-3-ethyl-2-piperidone.

9. 3,3-dipheny1-2-piperidone.

LEWIS A. WALTER. RICHARD H. BARRY. 5

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS m Number Name Date 2,383,444 Bruson Aug. 28, 1945 Number Aschan FOREIGN PATENTS Country Date Germany Nov. 30, 1896 Great Britain Feb. 17, 1917 Germany Jan. 23, 1933 Germany Apr. 7, 1933 Germany Nov. 22, 1937 OTHER REFERENCES Ber der Deu. Chem, 23, 3694 and. 

1. A 2-PIPERIDONE HAVING THE FORMULA: 